A federal appeals court is expressing skepticism about the CIA's claim that its technique for briefing presidents is so sensitive that it must be protected from public scrutiny, even 40 years after the fact.

Two judges considering a lawsuit seeking access to so-called Presidential Daily Briefs provided to President Johnson during the Vietnam War era cast doubt yesterday on the spy agency's assertion that the way it updates the nation's chief executive is itself an intelligence method entitled to blanket secrecy under the law.

"It just doesn't compute to me," Judge Pamela Ann Rymer of the 9th Circuit Court of Appeals said as a three-judge panel heard oral arguments on the case.

"It's not as if PDBs have never been made public or they haven't been talked about," Judge Raymond Fisher said. He noted that some have been officially released and that a book, "Bush at War" by Bob Woodward, quotes from a CIA brief prepared on the day after the terrorist attacks of September 11, 2001.

A Justice Department attorney, Mark Stern, told the court that disclosing the amount of detail provided to presidents and "what sort of things they care about" could undermine national security. "This is the crystallization of intelligence," he said.

The suit was brought by a political science professor at the University of California at Davis, Larry Berman, as part of research he was doing on how political leaders in America responded to developments in the Vietnam War. At issue are just two PDBs he requested under the Freedom of Information Act, one from August 1965 and another from April 1968.

As part of his research, the professor discovered that the Johnson Presidential Library in Austin, Texas, released several briefs in part. The CIA now says that was a mistake, but Mr. Berman said in an interview that the release confirms that PDBs are more pedestrian than Langley acknowledges. "Even the reviewing archivists didn't recognize them as PDBs," the professor said in an interview. Last year, a federal district judge in Sacramento ruled against Mr. Berman. Judge David Levi upheld the CIA's right to withhold the entire series of presidential briefs without a document-by-document review. He based his ruling on a variety of grounds, including the claim that briefing techniques are protected intelligence methods.